Methods and apparatus for polishing an edge of a substrate

ABSTRACT

Methods for polishing an edge of a substrate are provided. The invention includes rotating a substrate against a polishing film so as to remove material from the edge of the substrate; and detecting an amount of force exerted in pressing the polishing film against the substrate. Numerous other aspects are provided.

This application is a division of, and claims priority to, U.S. Non-Provisional patent application Ser. No. 11/693,695, filed Mar. 29, 2007, and titled, “METHODS AND APPARATUS FOR POLISHING AN EDGE OF A SUBSTRATE” (Attorney Docket No. 10560), which claims priority to U.S. Provisional Patent Application Ser. No. 60/787,438, filed Mar. 30, 2006, and entitled “METHODS AND APPARATUS FOR PROCESSING A SUBSTRATE” (Attorney Docket No. 10560/L). Both of these patent applications are incorporated by reference herein in their entirety for all purposes.

CROSS-REFERENCE TO RELATED APPLICATIONS

Further, the present application is related to the following commonly-assigned, co-pending U.S. patent applications, each of which is hereby incorporated herein by reference in its entirety for all purposes:

U.S. patent application Ser. No. 11/298,555 filed on Dec. 9, 2005 and entitled “METHODS AND APPARATUS FOR PROCESSING A SUBSTRATE” Attorney Docket No. 10414); and

U.S. patent application Ser. No. 11/299,295 filed on Dec. 9, 2005 and entitled “METHODS AND APPARATUS FOR PROCESSING A SUBSTRATE” (Attorney Docket No. 10121).

FIELD OF THE INVENTION

The present invention relates generally to substrate processing, and more particularly to methods and apparatus for polishing an edge of a substrate.

BACKGROUND OF THE INVENTION

Conventional systems, which contact a substrate edge with an abrasive film to clean the edge, may not thoroughly polish or clean the edge. For example, the abrasive film may not sufficiently contact both bevels of the edge during cleaning. Additionally, the abrasive film may become worn from use, and therefore, lose its ability to sufficiently clean the substrate and require frequent replacement, which may affect semiconductor device manufacturing throughput. Accordingly improved methods and apparatus for cleaning an edge of a substrate are desired.

SUMMARY OF THE INVENTION

In a first aspect of the invention, a method of polishing an edge of a substrate is provided. The method includes (1) rotating a substrate against a polishing film so as to remove material from the edge of the substrate and (2) detecting an amount of one of energy and torque exerted in rotating the substrate against the polishing film. Embodiments of the method further include (3) determining an amount of material removed from the edge of the substrate based on the detected energy or torque exerted in rotating the substrate against the polishing film; (4) ascertaining a difference between the determined amount of material removed and a preset polish level; and (5) determining an amount of energy or torque to be exerted in rotating the substrate adapted to attain the preset polish level based on the difference between the determined amount of material removed and the preset polish level.

In a second aspect of the invention, an alternative method of polishing an edge of a substrate is provided. The method includes (1) rotating a substrate against a polishing film so as to remove material from the edge of the substrate and (2) detecting an amount of force exerted in pressing the polishing film against the substrate. Embodiments of the method include (3) determining an amount of material removed from the edge of the substrate based on the detected force exerted in pressing the polishing film against the rotating substrate; (4) ascertaining a difference between the determined amount of material removed and a preset polish level; and (5) determining a level of force to be applied to the polishing film adapted to attain the preset polish level based on the difference between the determined amount of material removed and the preset polish level and adjusting the force to the determined level.

In a third aspect of the invention, a system adapted to polish an edge of a substrate comprising is provided. The system includes (1) a substrate rotation driver adapted to rotate the edge of a substrate against a polishing film and (2) a first sensor coupled to the rotation driver adapted to detect one of an energy and torque exerted by the substrate rotation driver as it rotates the substrate against the polishing film. Embodiments of the system further include (3) a controller coupled to the first sensor and to the substrate rotation driver adapted to receive from the first sensor a signal indicative of the detected energy or torque exerted by the substrate rotation driver and adapted to transmit control signals to the substrate rotation driver based on the detected energy or torque exerted.

In a fourth aspect of the invention, an apparatus adapted to apply a preset pressure to a polishing film in contact with an edge of a substrate is provided. The apparatus includes (1) an actuator adapted to apply a preset pressure to the polishing film and (2) a controller coupled to the actuator and adapted to receive a signal indicative of a condition of the edge of the substrate, and to adjust a pressure applied by the actuator to the polishing film so as to maintain the preset pressure based on the received signal.

Other features and aspects of the present invention will become more fully apparent from the following detailed description, the appended claims and the accompanying drawings.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 is a schematic illustration of a cross-section of a portion of a substrate.

FIG. 2 is a schematic illustration depicting an example embodiment of an edge cleaning apparatus according to the present invention.

FIGS. 3A and 3B are close-up front and side cross-sectional schematic views, respectively, of a portion of the edge cleaning apparatus of FIG. 2.

FIG. 4 is a perspective view depicting an example embodiment of an edge cleaning apparatus according to the present invention.

FIG. 5 is a perspective view depicting another example embodiment of an edge cleaning apparatus according to the present invention.

FIG. 6 is a perspective view of a portion of the example embodiment depicted in FIG. 5.

FIGS. 7A and 7B are close-up perspective views of different embodiments of replaceable cassettes for use with embodiments of the present invention.

FIGS. 8A through 8C are close-up perspective views of different embodiments of pads for use with embodiments of the present invention.

FIGS. 9A through 9C are plan views of examples of different possible head positions of the example edge polishing apparatus of FIG. 4.

FIGS. 10A through 10C are plan views of examples of different possible head positions of the example edge polishing apparatus of FIG. 5.

FIG. 11 is a perspective view of an embodiment of a multiple head edge polishing apparatus according to the present invention.

FIG. 12 is a perspective view of another embodiment of a multiple head edge polishing apparatus according to the present invention.

FIG. 13 is a perspective view of yet another embodiment of a multiple head edge polishing apparatus according to the present invention.

FIG. 14 is a schematic illustration depicting an example embodiment of an edge cleaning apparatus according to the present invention.

DETAILED DESCRIPTION

The present invention provides improved methods and apparatus for cleaning and/or polishing the edge of a substrate. With reference to FIG. 1, a substrate 100 may include two major surfaces 102, 102′ and an edge 104. Each major surface 102, 102′ of the substrate 100 may include a device region 106, 106′ and an exclusion region 108, 108′. (Typically however, only one of the two major surfaces 102, 102′ will include a device region and an exclusion region.) The exclusion regions 108, 108′ may serve as buffers between the device regions 106, 106′ and the edge 104. The edge 104 of a substrate 100 may include an outer edge 110 and bevels 112, 114. The bevels 112, 114 may be located between the outer edge 110 and the exclusion regions 108, 108′ of the two major surfaces 102, 102′. The present invention is adapted to clean and/or polish the outer edge 110 and at least one bevel 112, 114 of a substrate 100 without affecting the device regions 106, 106′. In some embodiments, all or part of the exclusion regions 108, 108′ may be cleaned or polished as well.

The present invention provides a frame for supporting a film (e.g., an abrasive polishing film) or abrasive buffer against the edge 104 of a substrate 100 as the substrate 100 is rotated (e.g., by a vacuum chuck, drive rollers, etc.). The film may be pressed against the rotating substrate edge 104 using a pad pushed by an actuator and/or an inflatable pad. In either case, the pad and/or inflatable pad may be soft and/or include or develop contours to conform with the shape of the substrate edge 104. Depending on the amount of force applied by the actuator, the resiliency of the pad selected, the amount of inflation of an inflatable pad, and/or the amount of tension on the film, a controlled amount of pressure may be applied to polish the edge 104. Alternatively or additionally, the film may be under tension within the frame such that the film itself is adapted to apply a variable amount of tension to the substrate edge 104 and to contour to both the outer edge 110 and at least one of the bevels 112, 114 (e.g., with or without additional support from a pad). Thus, the present invention provides precise control of an edge polish process which may be used to compensate for different edge geometries and changes in the substrate 100 as material is removed from the edge 104.

In some embodiments, the frame may support multiple polishing heads, each head being adapted to support polishing film. The polishing heads may support different types of films (e.g., films of different abrasive grits) which may be used concurrently, in a predefined sequence, or at different times. The heads may be disposed in different positions and in different orientations (e.g., aligned with the edge 104, normal to the edge 104, angled relative to the edge 104, etc.) to allow the supported films to polish different portions of the edge 104 of the rotating substrate 100. The heads may be adapted to be oscillated or moved (e.g., angularly translated about a tangential axis of the substrate 100 and/or circumferentially relative to the substrate 100) around or along the edge 104 by the frame so as to polish different portions of the edge 104. In some embodiments, the heads may continuously oscillate around or along the rotating edge 104 of the substrate 100. Each head may include an indexed spool of film and/or be contained in a replaceable cassette. An indexed spool may allow a precise amount of film to be advanced to position unused film for polishing. In some embodiments, two indexed spools may be used to allow film to be moved back and forth between the spools.

Additionally or alternatively, the present invention may include facilities to deliver fluids to the substrate edge 104 being polished. In some embodiments, one or more channels may be provided to direct chemicals or water to the substrate edge 104 to assist in the polishing and/or to wash away particles resulting from the polishing. The chemicals may be sprayed directly onto the substrate 100, at the substrate/polishing film interface, and/or may be applied to and/or through the film and/or pad. The fluids may be sprayed from either or both sides of the substrate 100 and the present invention may employ gravity or suction to cause the runoff not to contaminate or contact other parts of the substrate 100 or apparatus of the invention. Further, energy (e.g., megasonic energy) may be applied to the substrate edge 104 via fluid carrying such energy.

The substrate 100 may be rotated in a horizontal plane. The edge 104 of the substrate 100 may be aligned with or normal to the polishing film, pad, and/or polishing head. In additional or alternative embodiments, the substrate 100 may be rotated in a vertical plane, other non-horizontal plane, and/or be moved between different planes of rotation.

In some embodiments, the driver(s) used to rotate the substrate 100 and the actuator used to push the pad and/or polishing film against the substrate edge 104 may be controlled by a controller. Likewise, operation of the indexed spool(s) and/or the fluid channels may also be under the direction of a controller. The controller may be adapted to receive feedback signals from the driver and/or actuator that indicate: (1) an amount of energy and/or torque being exerted to drive the substrate 100 (e.g., rotate a vacuum chuck holding the substrate 100) and/or (2) an amount of force applied to the actuator to push the pad/polishing film against the substrate 100, respectively. These feedback signals may be employed to determine an amount of material that has been removed from the edge of the substrate 100, which may include, for example, whether a particular layer of material has been removed and/or whether an intended edge profile has been reached. For example, a reduction in the torque of the rotating substrate 100 (or energy expended in rotating the substrate 100) during a polishing procedure may indicate a reduction in friction between the substrate 100 and the polishing film and/or pad. The reduction in torque or rotational energy may correspond to an amount of material removed from the edge of the substrate 100 at or near points of contact between the substrate 100 and the polishing film and/or a characteristic edge profile (e.g., a shape, curvature or smoothness level at the edge of the substrate 100).

Alternatively or additionally, a friction sensor positioned in contact with the edge of the substrate may provide signals indicative of an amount of material that has been removed from the substrate 100.

Turning to FIG. 2, a schematic view of an edge polishing apparatus 200 is depicted. A frame 202 supports and tensions a polishing film 204 in a plane perpendicular to the major surfaces 102, 102′ of a substrate 100 such that the edge 104 of the substrate 100 may be pressed against (e.g., as indicated by the straight downward arrows 205 a, 205 b) the polishing film 204 and the polishing film 204 may contour to the substrate edge 104. As indicated by the curved arrow 205 c, the substrate 100 may be rotated against the polishing film 204. The substrate 100 may be rotated at a rate ranging from about 50 to 300 RPM, for example, although other rates may be used. The substrate 100 may contact the polishing film 204 for about 15 to 150 seconds depending on the type of film used, the grit of the film, the rate of rotation, the amount of polishing required, etc. More or less time may be used. In some embodiments, the polishing film 204 may be supported by a pad 206 disposed adjacent a backside (e.g., a non-abrasive side) of the polishing film 204 and mounted on the frame 202. As indicated by the straight upward pointing arrow 207, the frame 202 including the tensioned polishing film 204 and/or the pad 206 may be pushed against the edge 104 of the substrate 100. In some embodiments, the substrate 100 may be pushed against the polishing film with an amount of force ranging from about 0.5 lbs. to about 2.0 lbs. Other amounts of force may be used.

Additionally or alternatively, an additional length of the polishing film 204 may be supported and tensioned by spools 208, 210 mounted to the frame 202. A supply spool 208 may include unused polishing film 204 available to be unwound and pulled into position adjacent the substrate 100 while a take-up spool 210 may be adapted to receive used and/or worn polishing film 204. One or both of the spools 208, 210 may be indexed to precisely control the amount of polishing film 204 that is advanced. The polishing film 204 may be made from many different materials including aluminum oxide, silicon oxide, silicon carbide, etc. Other materials may also be used. In some embodiments, the abrasives used may range from about 0.5 microns up to about 3 microns in size although other sizes may be used. The abrasives may also be of different shapes and textures. Different widths of polishing film 204 ranging from about 1 inch to about 1.5 inches may be used (although other widths may be used). In one or more embodiments, the polishing film may be about 0.002 to about 0.02 of an inch thick and be able to withstand about 1 to 5 lbs. of tension in embodiments that use a pad 206 and from about 3 to about 8 lbs. of tension in embodiments without a pad. Other films having different thicknesses and strengths may be used. The spools 208, 210 may be approximately 1 inch in diameter, hold about 500 inches of polishing film 204, and may be constructed from any practicable materials such as polyurethane, polyvinyl difluoride (PVDF), etc. Other materials may be used. The frame 202 may be constructed from any practicable materials such as aluminum, stainless steel, etc.

In some embodiments, one or more fluid channels 212 (e.g., a spray nozzle or bar) may be provided to deliver chemicals and/or water to aid in the polishing/cleaning of the substrate edge 104, lubricate the substrate, and/or to wash away removed material. The fluid channel 212 may be adapted to deliver fluid to the substrate 100, to the polishing film 204, and/or to the pad 206. The fluids may include deionized water which may serve as a lubricant and to flush particles away. A surfactant and/or other known cleaning chemistries may also be included. In some embodiments, sonic (e.g., megasonic) nozzles may be used to deliver sonicated fluids to the substrate edge 104 to supplement the cleaning. Fluid also may be delivered through the polishing film 204 and/or pad 206 to the edge 104.

Turning to FIGS. 3A and 3B, close-up front and side cross-sectional schematic views, respectively, of the polishing film 204 and pad 206 of FIG. 2 are depicted. Note that the forces (indicated by the straight arrows) cause the polishing film 204 and the pad 206 to contour and conform to the edge 104 of the substrate 100. In some embodiments, if the substrate 100 was not present, the pad 206 would have a flat surface where the substrate 100 is shown compressing the pad 206. Likewise, if the substrate 100 was not present, the polishing film 204 would lie flat and be represented by a straight line in both views.

Turning now to FIGS. 4 and 5, two additional alternative embodiments of an edge polishing apparatus 400, 500 are depicted. As shown in FIG. 4, an example edge polishing apparatus 400 may include a base or frame 402 that includes a head 404 which supports polishing film 204 tensioned between spools 208, 210 and further supported by a pad 206. As shown, the pad 206 may by mounted to the head 404 via a biasing device 406 (e.g., a spring). The edge polishing apparatus 400 of FIG. 4 also may include one or more drive rollers 408 (two shown) and guide rollers 410 (two shown) that are adapted to rotate the edge 104 of the substrate 100 against the polishing film 204. The drive rollers 408 may themselves each be driven by drivers 412 (e.g., motors, gears, belts, chains, etc.).

The drive rollers 408 and guide rollers 410 may include a groove that allows the rollers 408, 410 alone to support the substrate 100. In some embodiments the groove within the drive rollers 408 may have a diameter of approximately 2.5 inches and the groove within the guide rollers 410 may have a diameter of approximately 1 inch. Other dimensions are possible. The area of the drive rollers 408 in contact with the substrate 100 may include texturing or cross-grooves to allow the drive rollers 408 to grip the substrate 100. The drive rollers 408 and guide rollers 410 may be constructed from materials such as polyurethane, polyvinyl difluoride (PVDF), etc. Other materials may be used.

As shown in FIG. 5, another example edge polishing apparatus 500 may include a base or frame 502 that includes a head 504 which supports polishing film 204 tensioned between spools 208, 210 and further supported by a pad 206. As shown, the pad 206 may by mounted to the head 504 via an actuator 506 (e.g., a pneumatic slide, hydraulic ram, servo motor driven pusher, etc.). The edge polishing apparatus 500 of FIG. 5 also may include a vacuum chuck 508 coupled to a driver 510 (e.g., motor, gear, belt, chain, etc.). An advantage of the embodiment depicted in FIG. 5 is that the apparatus 500 does not need to contact the edge 104 being polished. Thus, the potential of particles accumulating on drive rollers and being re-deposited on the edge 104 is eliminated. The need to clean rollers also is eliminated. Further, the possibility of rollers damaging or scratching the edge is also eliminated. By holding the substrate in a vacuum chuck, high speed rotation without significant vibration may be achieved.

Turning now to FIGS. 6 through 8B, some details of features of the example embodiments of FIGS. 4 and 5 are described. Note that features from the different embodiments may be combined in many different practicable ways to serve different design principals or concerns.

FIG. 6 depicts details of the frame 502 including the head 504 of FIG. 5. As described above, a head 504 supports polishing film 204 tensioned between spools 208, 210. The frame 502 (that includes head 504) may be adapted to be angularly translated (relative to an axis that is tangential to the edge 104 of a substrate 100 held in the edge polishing apparatus 500 (FIG. 5)) by a driver 600 (e.g., a servo motor) and pivot 602. The angular translation of the frame (and polishing film 204) is described in more detail below with respect to FIGS. 9A through 10C.

Additionally, the spools 208, 210 that are mounted to the head 504, may be driven by one or more drivers 604 (e.g., servo motors). The drivers 604 may provide both an indexing capability to allow a specific amount of unused polishing film 204 to be advanced or continuously fed to the substrate edge, and a tensioning capability to allow the polishing film to be stretched taught and to apply pressure to the substrate edge.

As can more clearly be seen in FIG. 6 (as compared to FIG. 5), the optional pad 206 may by mounted to the head 504 via an actuator 506 that is adapted to adjustably press and contour the polishing film 204 against a substrate edge 104 (FIG. 5). Further, one or more support rollers 606 may also be mounted to the head 504 to guide and align the polishing film 204 in a plane perpendicular to the major surface 102 (FIG. 1) of a substrate 100 held in the edge polishing apparatus 500 (FIG. 5).

Note that in the embodiment depicted in FIGS. 5 and 6, the length of the polishing film 204 is disposed orthogonal to the edge 104 of a substrate 100 being polished. This is in contrast to the embodiment depicted in FIG. 2, wherein the longitudinal direction of the polishing film 204 is aligned with the edge 104 of a substrate 100 being polished. Other polishing film orientations and configurations may be employed. For example, the polishing film 204 may be held diagonally relative to the major surface 102 of the substrate 100.

Turning to FIGS. 7A and 7B, close-up perspective views of two different embodiments of replaceable cassettes 700A, 700B are depicted. Cassettes 700A, 700B may be adapted to provide the features of the head 404 and polishing film 204 in a disposable, refillable, and/or replaceable package which may be quickly and easily mounted on and/or removed from the frames 402, 502 of different edge polishing apparatuses 400, 500.

As shown in FIG. 7A, the cassette 700A may include head 404 which supports polishing film 204 which spans from supply reel 208 to take-up reel 210. The polishing film 204 may be guided and aligned by support rollers 606 mounted to the head 404. A pad 206 may be provided to further support the polishing film 204 as described above. Also as described above, a biasing device 406 (e.g., a spring) may be employed to mount the pad 206 to the head 404 to provide flexible, dynamic counter-pressure to the pad 206. Alternatively or additionally, an adjustable actuator 506 (FIG. 6) may be used to push the pad 206 against the polishing film 204 or to push the entire head 404 toward the substrate 100.

In yet another alternative embodiment, as shown in FIG. 7B, instead of a pad 206, the head 404 may simply rely on the tension of the polishing film 204 to provide lateral pressure to the substrate edge 104 (FIG. 1). In some embodiments, the head 404 may include a notch 702 as shown in FIG. 7B to accommodate the substrate 100.

Turning to FIGS. 8A and 8B, two different alternative embodiments of pads 206A, 206B are depicted. In addition to a pad 206 (FIG. 6) that has a flat surface co-planar with the polishing film 204 when a substrate is not present, a pad 206A may include a concave surface that matches the contour of the edge 104 of a substrate 100. Alternatively, as shown in FIG. 8B, the pad 206B may include a double concave surface to better match the contour of the edge 104 of a substrate 100. In yet other alternative embodiments, a pad 206 may include a shaped groove that precisely matches the contour of the edge 104 of a substrate 100 including the bevels 112, 114 and outer edge 110 (FIG. 1).

The pads 206, 206A, 206B may be made of material such as, for example, an acetal resin (e.g., Delrin® manufactured by DuPont Corporation), PVDF, polyurethane closed cell foam, silicon rubber, etc. Other materials may be used. Such materials may have a resilience or an ability to conform that is a function of the thickness or density of the pad. The material may be selected based upon its resilience, which, in turn, may be selected based upon the type of polishing required.

In some embodiments, the pad 206, 206A, 206B may have an adjustable amount of ability to conform to the substrate's edge. For example the pad 206, 206A, 206B may be or include an inflatable bladder such that by adding more air or liquid or other fluid, the pad becomes harder and by reducing the amount of air or liquid or other fluid in the bladder, the pad becomes more conforming. FIG. 8C depicts an embodiment of a pad 206C that includes an inflatable bladder 802 that may be filled (and/or emptied) via a fluid channel 804 with fluid from a fluid supply 806. In some embodiments, the fluid supply 806 may inflate/deflate the bladder 802 under the direction of an operator or a programmed and/or user operated controller. In such embodiments, an elastomeric material such as silicon rubber or the like, may be used for the bladder 802 to further enhance the pad's ability to stretch and conform to the substrate's edge 104. Such an embodiment would allow an operator/controller to precisely control how far beyond the bevels 112, 114 (if at all) and into the exclusion region 108 and/or 108′ (FIG. 1) the polishing film 204 is made to contact the substrate 100 by, e.g., limiting the amount of fluid pumped into the bladder 802. For example, once a substrate outer edge 110 is placed against a pad 206C with a deflated bladder 802, the bladder 802 may be inflated so that the pad 206C is forced to wrap around and conform to the outer edge 110 and bevel(s) 112, 114 of the substrate 100 without wrapping around to the device region 106, 106′ of the substrate 100. Note that in some embodiments, multiple bladders may be used in a pad and that differently shaped inflatable bladders may be used within differently shaped pads 206, 206A, 206B.

In some embodiments, fluids used to aid in the polishing may be delivered to the substrate edge via the pads 206, 206A, 206B. A fluid channel may be provided to drip or spray the fluid on or into the pads. Alternatively, an inflatable pad may include a bladder with a semi-permeable membrane that allows fluid to be slowly released and transmitted to the polishing film 204 (e.g., through the pad). In such embodiments, the pads 206, 206A, 206B may be covered by, made of, and/or include material that absorbs and/or retains the fluids used (e.g., polyvinyl alcohol (PVA), etc.).

FIGS. 9A through 9C and FIGS. 10A through 10C depict examples of different possible head positions of the alternative edge polishing apparatuses 400, 500 respectively, described above. The present invention is adapted to bring polishing film 204 in contact with the bevels 112, 114, and outer edge 110 of a substrate 100 without contacting the device region 106 of the substrate 100. In operation, this is achieved by angularly translating a head 404, 504 (and consequently, a portion of polishing film in contact with and contoured to the edge 104 of a substrate 100) around an axis that is tangential to the outer edge 110 of the substrate 100 as it is rotated. Referring to FIGS. 9A through 9C and FIGS. 10A through 10C, this axis of angular translation may be represented by a line extending perpendicular out of the paper upon which the FIGs. are drawn at the point labeled “P.” The heads 404, 504 may be held in various positions to clean desired portions of the substrate edge 104 as the substrate 100 is rotated. In some embodiments, the heads 404, 504 may be adapted to continuously or intermittently oscillate between the various positions depicted and/or other positions. The heads 404, 504 may be moved on the frame 502 by drivers 600 (FIG. 6) under the direction of a programmed or user operated controller. Alternatively, the heads 404, 504 may be fixed and/or only adjusted while the substrate is not being rotated. In yet other embodiments, the substrate may be held fixed while the heads are oscillated (as described above) as well as rotated circumferentially around the substrate 100. Further, the polishing film 204 may be mounted on the heads 404, 504 in a continuous loop and/or the polishing film 204 may be continuously (or intermittently) advanced to polish and/or increase the polishing effect on the substrate edge 104. For example, the advancement of the film 204 may be used to create and/or enhance the polishing motion. In some embodiments the film 204 may be oscillated back and forth to polish and/or enhance the polishing effect on a stationary or rotating substrate 100. In some embodiments, the film 204 may be held stationary during polishing. Further, the film 204 tension and/or force 207 (FIG. 2) may be varied based on various factors including, for example, the angle and/or position of the polishing film 204, the polishing time, the materials used in the substrate, the layer being polished, the amount of material removed, the speed at which the substrate is being rotated, the amount of current being drawn by the driver rotating the substrate, etc. Any combination of the above described polishing motions and/or methods that are practicable may be employed. These methods provide additional control over the edge polish process which can be used to compensate for geometry and changes in the material being removed as the film 204 is rotated/move about or relative to the edge 104.

Turning to FIGS. 11 through 12, additional embodiments of an edge polishing apparatus are depicted. FIG. 11 depicts an edge polishing apparatus 1100 including three heads 404, FIG. 12 depicts an edge polishing apparatus 1200 including two heads 504, and FIG. 13 depicts an edge polishing apparatus 1300 including four heads 1304. As suggested by the drawings, any number and type of heads 404, 504, 1304 may be used in any practicable combination. In addition, in such multi-head embodiments, each head 404, 504, 1304 may used a differently configured or type of polishing film 204 (e.g., different grits, materials, tensions, pressures, etc.). Any number of heads 404, 504, 1304 may be used concurrently, individually, and/or in a sequence. Different heads 404, 504, 1304 may be used for different substrates 100 or different types of substrates. For example, a first head 404 with a stiff biasing device 406 supporting a pad 206 such as the concave pad 206B and a coarse grit polishing film 204 may initially be used to remove a relatively large amount of rough material from the substrate bevels 112, 114 (FIG. 1). The first head 404 may be appropriately positioned to access the bevels 112, 114. After cleaning with the first head 404 is completed, the first head 404 may be backed away from the substrate 100, and a second head 504 with a fine grit polishing film 204 (and without a pad) may be moved into position to polish the bevels 112, 114 and the outer edge 110.

After cleaning one or more substrates 100, the portion of the polishing film 204 employed for such cleaning may become worn. Therefore, the take-up reel 210 (FIG. 4) may be driven to draw the polishing film 204 by a fixed amount from the supply reel 210 (FIG. 4) toward the take-up reel 210. In this manner, an unused portion of the polishing film 204 may be provided between the take-up reel 210 and supply reel 208. The unused portion of the polishing film 204 may be employed to subsequently clean one or more other substrates 100 in a manner similar to that described above. Consequently, the apparatus 1100, 1200 may replace a worn portion of polishing film 204 with an unused portion with little or no impact on substrate processing throughput. Likewise, if replaceable cassettes 700A are employed, impact on throughput may be minimized by quickly replacing the cassettes 700A when all the polishing film 204 in the cassette 700A is used.

Regarding the example embodiment of an edge polishing apparatus 1300 of FIG. 13 specifically, a frame 1302 that supports multiple heads 1304 is depicted in schematic form. The heads 1304 are each mounted to the frame 1302 and each include an actuator 1306 (e.g., pneumatic piston, servo driven slide, hydraulic ram, etc.) adapted to press a pad 206 and a length of polishing film 204 against the edge 104 of a substrate 100 in response to a control signal from a controller 1308 (e.g., a programmed computer, an operator directed valve system, an embedded real time processor, etc.). Note that the controller 1308 is coupled (e.g., electrically, mechanically, pneumatically, hydraulically, etc.) to each of the actuators 1306.

In addition, a fluid supply 806 may be coupled to and under the control of the controller 1308. The fluid supply 806 may be controlled to independently deliver fluids (e.g., DI water, cleaning chemistry, sonicated fluids, gas, air, etc.) to each of the heads 1304 via one or more fluid channels 212. Under the direction of the controller 1308, various fluids may be selectively delivered to the pads 206, the polishing film 204, and/or the substrate edge 104 via the fluid channels 212. The fluid may be for use in polishing, lubricating, particle removal/rinsing, and/or inflating a bladder 802 (FIG. 8C) within the pads 206. For example, in some embodiments, the same fluid delivered through a permeable pad 206 may be used for both polishing and inflating the pad 206 while a different fluid, delivered to the same head 1304 via a second channel (not shown) is used for rinsing and lubricating.

Turning to FIG. 14, a schematic view of an embodiment of the present invention similar to the example edge polishing apparatus 200 of FIG. 2 is depicted. As with the embodiment of FIG. 2, a frame 202 supports and tensions a polishing film 204 in a plane perpendicular to the major surfaces 102, 102′ (FIG. 1) of a substrate 100 such that the edge 104 of the substrate 100 may be pressed against (e.g., as indicated by the straight downward arrows 205 a, 205 b) the polishing film 204 and the polishing film 204 may contour to the substrate edge 104. As indicated by the curved arrow 205 c, the substrate 100 may be rotated against the polishing film 204. The polishing film 204 may be supported by a pad 206 disposed adjacent a backside of the polishing film 204 and mounted on the frame 202. As indicated by the straight upward pointing arrow 207, the frame 202 including the tensioned polishing film 204 and/or the pad 206 may be pushed against the edge 104 of the substrate 100. The polishing film 204 may be supported and tensioned by spools 208, 210 mounted to the frame 202. A supply spool 208 may include unused polishing film 204 available to be unwound and pulled into position adjacent the substrate 100 while a take-up spool 210 may be adapted to receive used and/or worn polishing film 204. One or both of the spools 208, 210 may be indexed to precisely control the amount of polishing film 204 that is advanced. One or more fluid channels 212 may be provided to deliver chemicals and/or water to aid in the polishing/cleaning of the substrate edge 104, lubricate the substrate, and/or to wash away removed material. The fluid channel 212 may be adapted to deliver fluid to the substrate 100, to the polishing film 204, and/or to the pad 206.

The embodiment of FIG. 14 further includes a controller 1308 (e.g., a software driven computer, a programmed processor, a gate array, a logic circuit, etc.) adapted to direct the operation of a driver 1402 which may be used to rotate the substrate 100. The driver 1402 may be embodied, for example, as a motor adapted to rotate a vacuum chuck, drive rollers, etc. The controller 1308 may transmit or output a control and/or power signal to the driver 1402 via a signal line 1404. Further, the controller 1308 may be adapted to receive one or more feedback or information signals from the driver 1402 via one or more signal lines 1406. As noted above, the feedback or information signals from the driver 1402 may provide various indications about the status of the driver 1402, the edge polishing apparatus 202, and/or the substrate 100. For example, the rotational speed of the driver 1402 may be determined from a signal that indicates the amount of current drawn by a motor within the driver 1402. Alternatively, a sensor (not shown) within the driver 1402 may be employed to generate a signal indicative of the torque of the platform (e.g., vacuum chuck) holding the substrate 100 as it is rotated by the driver 1402 and/or the energy being exerted by the driver 1402 to rotate the substrate 100 via the platform.

The information signal(s) on the signal line(s) 1406 may be used to monitor the polishing progress of the edge polishing apparatus 202. For example, a change in the current drawn by a motor within the driver 1402 as indicated by a feedback signal on signal line 1406 may be interpreted by the controller 1308 as an indication that the amount of friction between the edge polishing apparatus 202 and the substrate has changed. Assuming a constant force 207 is being maintained by the edge polishing apparatus 202 on the substrate 100, the controller 1308 may interpret the change in the amount of friction to mean that different material is now being polished. A substrate 100 that includes multiple layers of material including, for example, a film layer, may be comprised of different materials. Thus, the controller 1308 may determine that the change in current indicated on the signal line 1406 means that a layer of material has been removed from (e.g., polished off of) the edge 104 of the substrate 100. Additionally or alternatively, depending on the characteristics of the edge 104 of the substrate 100, the controller 1308 may interpret a change in the amount of friction to mean that a certain amount of material has been removed from the edge 104 and consequently, that the edge profile has changed.

The embodiment of FIG. 14 further includes an actuator 1408 adapted to be directed by the controller 1308. The actuator 1408 may be used to press the pad 206 and/or film 204 against the rotating the substrate 100. The actuator 1408 may be adapted to apply a constant force against the substrate or a variable force determined by the controller 1308. The actuator 1408 may be embodied, for example, as a pneumatic piston, a hydraulic ram, an electric solenoid, etc. The controller 1308 may transmit or output a control and/or power signal to the actuator 1408 via a signal line 1410. Further, the controller 1308 may be adapted to receive one or more feedback or information signals from the actuator 1408 via one or more signal line(s) 1412. The feedback or information signals from the actuator 1408 may provide various indications about the status of the actuator 1408, driver 1402, and/or the substrate 100. For example, the amount of force applied by the actuator 1408 may be determined from a signal that indicates the amount of current drawn by a solenoid within the actuator 1408. Alternatively, a sensor (e.g., a transducer, not shown) within the actuator 1408 may be employed to generate a signal indicative of the energy being exerted by the actuator 1408 to apply force to the substrate 100.

As with the information signal(s) on signal line(s) 1406, the signal(s) on line(s) 1412 may be used to monitor the polishing progress of the edge polishing apparatus 202. For example, as material is removed from the substrate 100 and the diameter of the substrate 100 is reduced, an actuator 1408 adapted to automatically maintain a fixed amount of force on the substrate 100 may adjust the position of, and/or applied force to, the pad 206 and/or polishing film 204. A signal on line 1412 may indicate this change and the controller 1308 may make a determination that a certain amount of material has been removed from (e.g., polished off of) the substrate 100 based on the signal.

The controller 1308 may use the feedback signals provided by the driver 1402 to determine whether a preset endpoint for edge polishing has been reached (e.g., a desired edge profile) and/or a difference between a current state of the edge 104 and the preset endpoint. For example, if the endpoint has been reached or the current state of the edge 104 is close to the endpoint (e.g., as measured in an amount of material that has been removed from the edge 104), then the controller 1308 may transmit signals to the driver 1402 to reduce the rotation speed of the substrate 100 so as to, in the former case, prevent further removal of material from the edge 104 or, in the latter case, to decrease the rate at which material is removed from the edge 104. Similarly, the controller 1308 may use feedback signals provided by the actuator 1408 to determine whether the preset endpoint has been reached or is close to being reached. The controller 1308 may transmit signals to the actuator 1408 to reduce an amount of force applied to the pad 206 and/or polishing film 204 to halt or slow removal of further material from the edge 104 in the event of such a determination.

The foregoing description discloses only exemplary embodiments of the invention. Modifications of the above disclosed apparatus and methods which fall within the scope of the invention will be readily apparent to those of ordinary skill in the art. For instance, although only examples of cleaning a round substrate are disclosed, the present invention could be modified to clean substrates having other shapes (e.g., a glass or polymer plate for flat panel displays). Further, although processing of a single substrate by the apparatus is shown above, in some embodiments, the apparatus may process a plurality of substrates concurrently. Further, the edge polishing apparatus 200 of the present invention may be integrated to other devices. For example, the apparatus 200 may be integrated into a major surface polisher or a substrate cleaner. Integrating a edge polishing module into an output station of a substrate polisher (e.g., the APPLIED MATERIALS, INC. Reflexion Oxide CMP System) exchanger offers a number of advantages. Such integration can take advantage of the substrate exchanger so that no additional substrate transport is required. Facilities such as de-ionized water and drains are already resident and access to the module through the polisher windows may be easily available. Additionally, such integration may be done without impacting the footprint of the tool. Further, particularly with applications which have relatively long process cycle times such as, for example, copper applications, there is sufficient time to polish the edges of the substrate without degrading the overall throughput of the tool.

Accordingly, while the present invention has been disclosed in connection with exemplary embodiments thereof, it should be understood that other embodiments may fall within the spirit and scope of the invention, as defined by the following claims. 

1. A method of polishing an edge of a substrate comprising: rotating a substrate against a polishing film so as to remove material from the edge of the substrate; and detecting an amount of force exerted in pressing the polishing film against the substrate.
 2. The method of claim 1, further comprising: determining an amount of material removed from the edge of the substrate based on the detected force exerted in pressing the polishing film against the rotating substrate.
 3. The method of claim 2, further comprising: determining a polishing end point has been reached.
 4. The method of claim 2, further comprising: determining whether an intended edge profile has been reached.
 5. The method of claim 2, further comprising: ascertaining a difference between the determined amount of material removed and a preset polish level.
 6. The method of claim 5, further comprising: determining a level of force to be applied to the polishing film adapted to attain the preset polish level based on the difference between the determined amount of material removed and the preset polish level.
 7. The method of claim 6, further comprising: adjusting the force to the determined level.
 8. The method of claim 5, further comprising: ascertaining from the amount of material that has been removed from the substrate edge whether a layer of material has been removed.
 9. The method of claim 8, further comprising: reducing a rotation speed of the substrate if the removed layer is an endpoint.
 10. The method of claim 1, further comprising: reducing friction between the substrate and the polishing film by delivering a fluid to the polishing film.
 11. The method of claim 1, further comprising: removing particles from the edge of the substrate by delivering a fluid to the polishing film during contact with the substrate.
 12. The method of claim 11, wherein delivering a fluid further comprises: spraying the fluid onto the substrate.
 13. The method of claim 1, wherein detecting the amount of exerted force further comprises: receiving a feedback signal from at least one of a driver and an actuator.
 14. The method of claim 1, further comprising: rotating the substrate against the polishing film for about 15 to 150 seconds.
 15. The method of claim 1, further comprising: rotating the substrate at a rate ranging between 50 and 300 RPMs.
 16. The method of claim 1, further comprising: angularly translating the polishing film against the substrate.
 17. The method of claim 1, further comprising: advancing the polishing film as the polishing film contacts the substrate.
 18. The method of claim 1, further comprising: contouring the polishing film to an edge of the substrate.
 19. The method of claim 1, further comprising: monitoring a polishing process.
 20. The method of claim 1, wherein detecting the amount of force further comprises: detecting an amount of current drawn to apply the force. 